Same VLAN as Native and Trunk

[network_geek]

Hi All,

I faced a very strange issue and I am trying to dig down the exact cause for this. I had deployed new servers and connected them to a stack of 3850s. I tried creating a port-channel and the limitations of server prohibited me from doing so. I then decided to use physical interfaces only. I tried configuring interfaces as either trunk or access but it was no good. I was using VLAN of 120 for management. Once I allowed 120 as native(switchport trunk native vlan 120) and as well as tagged(switchport trunk allowed vlan 120) on trunk port the connectivity got established. Can someone help me out in finding the reason for this?

Thanks in advance.

[paul driver · Accepted solution]

Hello

Vlan 120 traffic was being sent untagged from the servers so when you specified that vlan as native you got connection,Obviously you needed to allow vlan 120 over the trunk also?

[network_geek]

Hi Paul,

Thank you for your update. While allowing the same tag as native allows me the capability of sending untagged traffic on a trunk interface but tagging it makes native VLAN useless when are talking about the same tag. Doesn't it contradict itself or my idea of native VLAN is not correct?

What I mean here is if I have allowed untagged traffic of VLAN120(native VLAN) to pass through trunk(VLAN Tag 120) and under that I am also allowing it as tagged.

Can you kindly guide me on this?

[network_geek]

Hi All,

Can anyone help me understand what actually happened.